1. Field of the Invention
The present invention relates to a riveting device, particularly to a riveting device adaptive to any screw head.
2. Description of the Related Art
The current riveting devices must cooperate with a mandrel. The rivet nut is rotated clockwise and locked to the mandrel. Then, the user pulls the mandrel backward with force to fasten the rivet nut. After riveting is completed, the rivet nut is fastened to the workpiece. Then, the user rotates the mandrel counterclockwise to separate the mandrel from the rivet. All the riveting devices available in the market use dedicated mandrels. In other words, each manufacturer has its own mandrel design. The mandrel must match the thread specification of the rivet nut. Sometimes, the mandrel of the riveting device does not match the rivet nut available for the user. For example, the riveting device adopts a metric system mandrel but the rivet nut has an inch screw thread. If the mandrel fractures, the user has to find the same mandrel manufactured by the original manufacturer. However, the local importers do not necessarily import the required products.
The manufacturers are also troubled by the same problem that the mandrel must match the rivet nut. There are many specifications of threads. The mandrel has to match the rivet nut in the thread specification.
Thus, the amount of manufacture and stock become a problem. Some thread specifications are very rare. Maybe, less than 50 pieces of rare-specification mandrels are sold within 10 years. However, the rare-specification mandrels must be mass-produced. Sometimes, the user directly contacts the manufacture to enquire a mandrel, which involves transport charge and remittance charge and is neither convenient nor economical for both parties. There are pneumatic riveting devices using ready screws as mandrels in the market. However, these pneumatic riveting devices only adopt hexagon socket head cap screws as mandrels. Refer to FIG. 1. The size of the guide sleeve 10 varies with the diameter of the screw 12. The fastening element 14 is an indispensable element that enables the screw 12 to rotate synchronously with the components inside the riveting device. In a manual riveting device, one end of the mandrel must be fastened to a component inside the riveting device. The user rotates the component so as to rotate the mandrel clockwise and counterclockwise. In other words, the mandrel and the component must rotate synchronously. In application, the user screws the rivet nut to the mandrel before riveting and then rotates the mandrel to separate (unscrew) the mandrel from the rivet after riveting. The pneumatic riveting device operates in the same principle except the component is driven by a pneumatic motor. In order to prevent the screw 12 from rotating independently, the current design adopts the abovementioned fastening element 14 to overcome the problem. However, such a design has other problems: firstly, the user can only use a hexagon socket head cap screw as the mandrel; secondly, the hexagon sockets of hexagon socket head cap screws may respectively have different sizes. In other words, each type of hexagon socket head cap screws has its own dedicated fastening element 14. Thus, the user cannot use a hexagon socket head cap screw as the mandrel unless he has the dedicated fastening element 14 thereof.
Accordingly, the present invention proposes a riveting device to overcome the abovementioned problems.